WEDNESDAY, Dec. 12 (HealthDay News) -- Fainting isn't fun. For those who have ever suddenly and briefly lost consciousness, it's a disconcerting situation that typically triggers a thorough medical workup. Unfortunately, it's often tough for physicians to determine just what caused a first fainting episode.

A large new Danish study provides a nationwide picture of how one-time fainters fare over several years. The researchers found these people were 74 percent more likely to eventually be admitted to the hospital for heart attack or stroke and five times more likely to need a pacemaker or implantable cardioverter-defibrillator at some point in the future.

The study suggests that even low-risk people who faint need to be carefully evaluated.

"Patients, relatives and clinicians should be aware that syncope [fainting] in seemingly healthy people is associated with higher risks of death and that syncope may be a first symptom of cardiovascular disease," said Dr. Martin Ruwald, lead author of the study and now a postdoctoral research fellow at the University of Rochester Medical Center in Rochester, N.Y.

The study was published Dec. 12 in the Journal of the American College of Cardiology.

The researchers used the Danish health care system's extensive nationwide databases, which allowed them to include every patient in Denmark who had a first-time admission to an emergency department or hospital due to fainting from 2001 to 2009.

The authors then included only the 40 percent of patients who appeared to have no pre-existing health condition, based on their medical records and the pharmacy database that showed their use of medications for high blood pressure or diabetes.

The researchers tracked those roughly 37,000 people for about 4.5 years, comparing their results to those of more than 185,000 similar people who hadn't fainted. The data included men and women, and people of any socioeconomic status, age, ethnicity, with or without any insurance or health programs, and whether or not they were employed.

The investigators wanted to know if people in the group that had fainted were more likely to die prematurely, have recurrent fainting episodes, develop cardiovascular problems or have a heart device -- such as a pacemaker or implantable cardioverter-defibrillator.

Fainting is related to a sudden drop in blood pressure that leads to decreased blood flow in the brain. Vasovagal syncope -- the most common type -- usually has an obvious trigger such as emotional stress, pain, the sight of blood or prolonged standing, according to the U.S. National Institute of Neurological Disorders and Stroke.

The study suggests that fainting in seemingly healthy people may be a first symptom of a more severe underlying cardiovascular disease, the researchers found.

However, Ruwald noted that in some people, fainting may not signal a significant health issue. "Women in particular can experience [fainting] in the younger age groups due to vasovagal or reflex syncope and it is a quite frequent event," he explained.

But other times, vasovagal reactions aren't the cause of fainting. Many women in their 20s have low blood pressure and fainting is very common among them, Ruwald noted.

Nonetheless, Ruwald said that the data suggest that a 26-year-old healthy female who faints has more than twice the risk of death within a year and beyond than does a woman of the same age who has not fainted.

Dr. Suzanne Steinbaum, a preventive cardiologist at Lenox Hill Hospital in New York City, explained that while fainting is common, it's challenging to identify who is in danger and who is not. "Some people do well, some people don't do well, and some people die," she said. "This study suggests that although fainting could mean nothing if you're 44 or older, it could be a sign of cardiovascular disease. See your doctor if you faint."

Experts identified some limitations of the study. Steinbaum said the study design did not reveal what kind of workups patients got after they fainted and what factors may or may not have been identified.

Dr. Robert Sheldon, a professor of cardiac sciences at the Libin Cardiovascular Institute of Alberta, at the University of Calgary in Canada, wrote in an accompanying editorial that the study highlights some of the downsides of using administrative data rather than information gleaned from direct patient assessment.

Sheldon noted that the study authors knew nothing about the diagnosis of the patients in the study, their cause of death or how those who were healthy and fainted directly compared to others who fainted but had a known disease or health problem.

While the study found an association between fainting in otherwise healthy people and future heart complications, it did not establish cause-and-effect.